The image you've uploaded contains a set of geometric diagrams (a, b, c, and d) with angles marked in them. Each diagram appears to have a point O at the center with various lines and angles marked, suggesting these might involve problems related to circle geometry or angle properties.

To assist you better, please specify which particular diagram or problem you need help with. Additionally, if there are specific questions or conditions related to these diagrams that you want to address, please let me know!

If you need a general overview or explanation for all diagrams, I can also provide that. Let me know how you'd like to proceed!

Here are some follow-up questions to consider:

1. Would you like to solve for the unknown angles marked as expressions in the diagrams?
2. Do you need to verify any angle properties or relationships shown in the diagrams?
3. Is there a specific theorem or geometric principle you're supposed to apply to these diagrams?
4. Do you need explanations on how certain angle measures are derived in circle geometry?
5. Are there any specific calculations from these diagrams that you're struggling with?

Tip: When dealing with diagrams involving circles, remember that the angle at the center is twice the angle at the circumference subtended by the same arc. This principle might be helpful in solving these problems.